Torsional vibration characteristics analysis and vibration suppression research of compressor flexible rotor system considering fit clearance

Shale gas reciprocating compressors are usually faced with problems such as wide working conditions, multiple wells, and variable loads, which makes the torsional vibration of the compressor crankshaft serious. In addition, there is an inevitable fit clearance between the moving pairs of the shafting, which will increase the torsional amplitude value of the shafting and amplify the resonance risk. This paper presents a torsional vibration calculation method and a torsional vibration suppression technique for reciprocating compressor crankshaft systems, considering the influence of fit clearance and flexibility. A rigid-flexible coupling dynamic model of compressor crankshaft system that considers crosshead pin clearance is established by combining multibody dynamics, collision dynamics, and finite element method. The torsional angular displacement, angular velocity, and force characteristics of the compressor crankshaft system, considering fit clearance and part flexibility, are solved and analyzed. Additionally, the dynamic characteristics of the sliding bearings are determined by considering their clearance, using the finite difference method and the pressure disturbance method. A finite element model of the compressor crankshaft system considering the mixed clearances is constructed. The torsional vibration characteristics of the compressor crankshaft system are compared and analyzed under different fit clearances. The accuracy of the proposed model is validated through compressor on-site operation experiments. The speed error between the experimental and simulated results is found to be only 1.2%. Finally, research on clearance configuration optimization is conducted. The results demonstrate that with a crosshead pin clearance of 0.07 mm and a sliding bearing clearance of 0.1 mm, the angular displacement amplitude of the shafting is reduced by 1.76%, the peak value of rubbing is decreased by 29.49%, and the resonance point of the crankshaft system is minimized. This research offers theoretical guidance for ensuring the stable and reliable operation of compressors.